Dissertation / PhD Thesis/Book

PreJuSER-1301

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Structural and functional studies of a prokaryotic cyclic nucleotide-gated channel

Cukkemane, A. (Corresponding author)FZJ*

2008
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich

Please use a persistent id in citations: http://hdl.handle.net/2128/13951

Report No.: Juel-4270

Abstract: Ion channels gated by cyclic nucleotides have crucial roles in cardiac and neuronal excitability and in signal transduction of sensory neurons. On binding cyclic nucleotides these channels are activated, which results an increase in membrane conductance. Although a lot of information is available on the function of these channel proteins, the molecular events that relay ligand binding to channel activation is not well understood. Here, I studied ligand binding of prokaryotic cyclic nucleotide-activated K$^{+}$ channels. One of them, the mlCNG channel from the nitrogen-fixing bacterium Mesorhizobium loti was suitable for biophysical characterization. One of the key questions that I worked on was how gating of the channel affects its ligand binding properties? I performed ligand binding studies on the tetrameric mlCNG protein and its isolated cyclic nucleotide-binding domain (CNBD). Affinity of cyclic nucleotides to the full-length mlCNG protein and to the CNBD was determined using spectroscopic methods. Both, the mlCNG channel and the CNBD bind cAMP in a non-cooperative manner with similar binding affinity. These results indicate that either no appreciable binding energy is required for activation, or the conformational change in the CNBD is the activation step itself. Crystallography experiments were performed on the mlCNG channel. Two-dimensional crystals were obtained in which the channel proteins were ordered in a square lattice. The channel proteins were assembled as tetramers and were arranged in a head-to tail fashion. The crystal diffracts to 15 Å. This is an excellent starting condition for future work to eventually obtain a structure at atomic resolution.

Note: Record converted from VDB: 12.11.2012
Note: Köln, Univ., Diss., 2007

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Research Program(s):

1. Grundlagen für zukünftige Informationstechnologien (P42)

Appears in the scientific report 2008

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Database coverage:

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